• Korean Chemical Engineering Research
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• v.48 no.6
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• pp.684-689
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• 2010

We synthesized a variety of SAPO catalysts with various structure directing agents by the hydrothermal method and applied them to the D-xylose dehydration. Single or mixtures of organic amines, viz. tetraethylammonium hydroxide(TEAOH), dipropylamine(DPA), diethylamine(DEA), morpholine and diethanolamine(DEtA) were used as structure directing agents. The $N_2$-isotherm, $NH_3$-temperature programmed desorption(TPD) and temperature programmed oxidation(TPO) were conducted to characterize SAPO catalysts. Among tested SAPO catalysts, the SAPO-34 synthesized with morpholine showed the highest furfural yield. The external surface area as well as the surface concentration of acid sites appeared to affect the catalytic activity for the dehydration of xylose into furfural.

• Journal of Environmental Science International
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• v.27 no.2
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• pp.83-90
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• 2018

In this study, zeolite (Z-C2) was synthesized using a fusion/hydrothermal method on coal fly ash (FA) discharged from a thermal power plant in the Ulsan area and then analyzed via scanning electron microscopy (SEM) and X-ray diffraction (XRD). The Z-C2 was characterized in terms of mineralogical composition and morphological analysis. The XRD results showed that its peaks had the characteristics of Na-A zeolite in the range of $2{\theta}$ of 7.18~34.18. The SEM images confirmed that the Na-A zeolite crystals had a chamfered-edge crystal structure almost identical to that of the commercial zeolite. The adsorption kinetics of Cu, Co, Mn and Zn ions by Z-C2 were described better by the pseudo-second-order kinetic model more than by the pseudo-first-order kinetic model. The Langmuir model fitted the adsorption isotherm data better than the Freundlich model did. The maximum adsorption capacities of Cu, Co, Mn and Zn ions obtained from the Langmuir model were in the following order : Cu (94.7 mg/g) > Co (77.7 mg/g) > Mn (57.6 mg/g) > Zn (51.1 mg/g). These adsorption capacities are regarded as excellent compared to those of commercial zeolite.

• Korean Chemical Engineering Research
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• v.49 no.6
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• pp.798-803
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• 2011

IgY(Immunoglobulin Yolk) is a specific antibody in egg yolk, and it protects human body from virus and antigen. There are a lot of egg yolk components such as lipoprotein and protein. To separate IgY, HPLC(High Performance Liquid Chromatography) and precipitation were used in a batch mode and SMB(Simulated Moving Bed) was adopted for continuous purification of yolk proteins. IgY and other proteins in yolk were separated by using three-zone SMB chromatography. Before performing SMB experiments, batch chromatography and PIM(pulse input method) were performed to find operation parameters and adsorption isotherms. The results of batch chromatography were compared with simulated results using Aspen chromatography. To find the most suitable separation condition in SMB chromatography, simulations in $m_2$-$m_3$ plane on the triangle theory were carried out. $m_2$ = 0.18, $m_3$ = 1.0 and ${\Delta}$t = 419 s are the best conditions for the highest purity of IgY. With this operating parameters(flow rate in three zone and switching time), the purity of raffinate results in 98.39% from Aspen chromatography simulation. Most of the simulation reached steadystate within second recycle.

• Korean Journal of Materials Research
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• v.29 no.5
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• pp.336-341
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• 2019

The gas adsorption isotherm requires accurate measurement for the analysis of porous materials and is used as an index of surface area, pore distribution, and adsorption amount of gas. Basically, adsorption isotherms of porous materials are measured conventionally at 77K and 87K using liquid nitrogen and liquid argon. The cold volume calibration in this conventional method is done simply by splitting a sample cell into two zones (cold and warm volumes) by controlling the level sensor in a Dewar filled with liquid nitrogen or argon. As a result, BET measurement for textural properties is mainly limited to liquefied gases (i.e. $N_2$ or Ar) at atmospheric pressure. In order to independently investigate other gases (e.g. hydrogen isotopes) at cryogenic temperature, a novel temperature control system in the sample cell is required, and consequently cold volume calibration at various temperatures becomes more important. In this study, a cryocooler system is installed in a commercially available BET device to control the sample cell temperature, and the automated cold volume calibration method of temperature variation is introduced. This developed calibration method presents a reliable and reproducible method of cryogenic measurement for hydrogen isotope separation in porous materials, and also provides large flexibility for evaluating various other gases at various temperature.

• Composites Research
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• v.33 no.6
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• pp.336-340
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• 2020

In this study, carbon aerogels (CA) were prepared by sol-gel polycondensation of resorcinol and furfural in isopropanol using hexamethylenetetramine as a catalyst, and then directly drying the organic gels under isopropanol freeze-drying conditions, followed by carbonization under a nitrogen atmosphere. The preparation conditions of the CA were explored by changing the mole ratio of resorcinol to furfural. The effect of the preparation conditions on the pore structure of the CA was studied by nitrogen adsorption isotherms. The characteristics of the CA were studied by scanning and transition electron microscopy, and infrared spectrometry. The accessibility of pores and performance of the CA as an electrode in electric double layer capacitors were also electrochemically investigated. As a result, BET surface area and specific capacitance increased with the molar ratio of resorcinol to catalyst (R/C) ratio; the maximum values of 765 ㎡/g and 132 F/g were achieved at the R/C ratio of 200, respectively. Consequently, it was confirmed that increasing the R/C ratio increased the average pore size of the CA electrode, which improved the rate capability of the system.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.12
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• pp.2115-2123
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• 2000

This research was designed to investigate the mathematical model and kinetics of phenol desorption from spent activated carbon. elucidating the desorption characteristics of phenol in the case of using acetone. The Freundlich isotherm constant ($k_e$) is expressed as a function of temperature: $k_e(T)=0.1exp(797.297/T)$. The Freundlich isotherm constant(n) is a weak temperature function and is rarely affected by temperature below $50^{\circ}C$. whereas it is necessary to correct the n value with respect to temperature above $100^{\circ}C$ owing to significant deviation (~5%). Based on the assumption that the surface desorption reaction of phenol is rate limiting, the desorption model was developed. Desorption reaction constant($k_d$) was determined by means of fitting the theoretical results best to experimental ones. The Arrhenius relationships for $k_d$ was expressed by: $k_d(sec^{-1})=0.0479{\cdot}exp(-3037/T)$. The model was verified by comparing the experimental ones under different reaction conditions with the theoretical results determined by the previously estimated $k_d$. Since the difference between them is with 5%, it is expected that the desorption model of this research seems to be appropriate to explain the desorption of phenol from activated carbon by acetone. According to studies of the model. regeneration time and ratio was estimated as a function of temperature under present conditions as follows: (1) regeneration time : ${\tau}_{reg}(hr)=-0.08130T_c+8.4775$. (2) regeneration ratio : ${\eta}(%)=0.2210T_c+83.745$. The regeneration time at 15, 55, and $100^{\circ}C$. respectively. was 7, 4.2, and 0.35 hours, whereas the regeneration ratio was 87. 96. and 99%. respectively. Also. studies of the model would make it possible to determine the regeneration time and ratio under other specific conditions (temperature, applied acetone volume, amount of activated carbon, and initially adsorbed phenol amount).

• Korean Journal of Soil Science and Fertilizer
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• v.10 no.1
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• pp.55-60
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• 1977

In order to study the availability of soil P and applied P to rice plant under water-logged system, a pot experiment with five soils having different levels of available P (24, 64, 100, 144 and 231 ppm) under four levels of applied P (0, 30, 60 and 90 ppm) was conducted. The availability of P was measured in terms of plant performance and the behaviors of P in soils were studied through the fractionation of various forms of P and by measuring the adsorption and desorption characteristics. The results are summarized us following. 1. The rice plant responded to applied P in the soils containing less than 144 ppm of available P as measured by Lancaster's method in terms of number of tillers in early growth stages. However, when the response of rice plant to applied P was evaluated in terms of grain yield there was no response even in the soil containing 24 ppm of available P. 2. Applied P was fixed as Al-P at the early stages and converted into Fe-P at later stages. 3. The P adsorption maxima of soils measured by Langmuir's isotherm ranged from 70 to 100mg/100g. No relationships between the level of available P and P adsorption maxima were observed. 4. There was a trend that the higher the level of available P, the higher the release of water soluble p. 5. The reduction of soil increased the level of available P by the factor of 1.8 times of air dried soils.

• Korean Journal of Environmental Agriculture
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• v.14 no.2
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• pp.135-143
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• 1995

This study was conducted to investigate the adsorption characteristics, distribution coefficients, and movement of alachlor(2-chloro-2', 6'-dimethyl-N-(methoxymethyl) acetanilide) and chlorothalonil(tetrachloroisophthalonitrile) for the 3 soils sampled from major soil groups in Cheju Island. Namwon, Jeju, and Mureng soils used in this study were classified as black volcanic ash soil, dark brown volcanic ash soil and dark brown nonvolcanic soil, respectively. Organic carbon content and CEC of Namwon soil were very high and those of Mureung soil were very low. Linear and Freundlich adsorption isotherms were the best to fit the adsorption of alachlor and chlorothalonil in the soils. K value, Freundlich coefficient, of alachlor for Namwon soil was 21.38, being 5.4 and 97.2 times higher than that for Jeju and Mureung soils respectively. The values of chlorothalonil for the soils were similar to those of alachlor but were much higher than them. When Mureung, Jeju and Namwon soil columns were leached with a solution containing 10.25 mg/l of alachlor and 1.50 mg/l of chlorothalonil, alachlor was first detected at 0.265, 0.47, and 1.86 pore volume (PV) and chlorothalonil was 3.71, 4.7 and 17.5 PV, respectively. The pore volumes at $C/C_o=1$ of alachlor in the leachates from Mureung, Jeju and Namwon soil columns were 1.1, 3.7 and 6.6 PV and those at $C/C_o=0.2$ of chlorothalonil were 7.5, 8.5 and 27.5, respectively. This means that the deceasing order of the mobility of the chemicals in soils was Mureung soil>Jeju soil${\gg}$Namwon soil. The pore volumes detecting $C/C_o=0.5$ of alachlor and $C/C_o=0.05$ of chlorothalonil in leachate were positively correlated with the distribution coefficients for the soils.

• Applied Chemistry for Engineering
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• v.21 no.1
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• pp.63-70
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• 2010

Transition metal based spent catalysts (Ni-Mo and Co-Mo), which were scrapped from the petrochemical industry, were reused for the removal processes of volatile organic compounds (VOCs). Especially the optimum regeneration procedures were determined using the removal efficiency of VOCs. In this work, the spent Ni-Mo and spent Co-Mo catalysts were pretreated with different physic-chemical treatment procedure: 1) acid aqueous solution, 2) alkali solution, 3) chemical agent and 4) steam. The various characterization methods of spent and its regenerated catalysts were performed using nitrogen adsorption, X-ray diffraction (XRD) and scanning electron microscopy (SEM) equipped with an energy dispersive spectrometry (EDS). It was found that all spent catalysts were found to be potentially applicable catalysts for catalytic oxidation of benzene. The experimental results also indicated that among the employed physico-chemical pretreatment methods, the oxalic acid aqueous (0.1 N, $C_2H_2O_4$) pretreatment appeared to be the most efficient in increasing the catalytic activity, although the catalytic activity of spent Ni-Mo and spent Co-Mo catalysts in the oxidation of benzene were greatly dependent on the pretreatment conditions. The pretreated spent catalysts at optimum condition could be also applied for removing other aromatic compounds (Toluene/Xylene).

• Korean Chemical Engineering Research
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• v.54 no.1
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• pp.81-88
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• 2016

Limonene is orange flavored natural material that is mainly contained in mandarine and lemon peels. D-limonene was extracted from cold-storaged mandarine peel by using Soxhlet extractor at $120^{\circ}C$ for 2 hours with ethanol as solvent. Henry constants of d-limonene and impurity were calculated as $H_{Lim}=8.55$ and $H_{imp}=0.223$ from the result of HPLC analysis. 4-bed SMB of limonene simulation with $0.46{\times}25cm$ columns was conducted by using Aspen chromatography program. Then effective condition for purity was found by changing $m_2$ and $m_3$ values in triangle diagram. The highest purity was 98.59% at $m_2=2.57$, $m_3=9.55$. For this case, feed, desorbent, extract, and raffinate flow rates were 1 mL/min, 1.19 mL/min, 0.857 mL/min and 1.34 mL/min, respectively. Scale-up simulation was also conducted by increasing column diameter from 0.46 cm to 1.6 cm for getting the same efficiency. The increased flow rates were 12 mL/min, 14 mL/min, 10 mL/min, and 16 mL/min for feed, desorbent, extract, and raffinate. It was possible to scale-up with maintaining same limonene purity because linear isotherms of limonene and impurity were assumed.